diff options
Diffstat (limited to 'drivers/block/cfq-iosched.c')
| -rw-r--r-- | drivers/block/cfq-iosched.c | 1856 |
1 files changed, 1856 insertions, 0 deletions
diff --git a/drivers/block/cfq-iosched.c b/drivers/block/cfq-iosched.c new file mode 100644 index 000000000000..0ef7a0065ece --- /dev/null +++ b/drivers/block/cfq-iosched.c @@ -0,0 +1,1856 @@ +/* + * linux/drivers/block/cfq-iosched.c + * + * CFQ, or complete fairness queueing, disk scheduler. + * + * Based on ideas from a previously unfinished io + * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. + * + * Copyright (C) 2003 Jens Axboe <axboe@suse.de> + */ +#include <linux/kernel.h> +#include <linux/fs.h> +#include <linux/blkdev.h> +#include <linux/elevator.h> +#include <linux/bio.h> +#include <linux/config.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/compiler.h> +#include <linux/hash.h> +#include <linux/rbtree.h> +#include <linux/mempool.h> + +static unsigned long max_elapsed_crq; +static unsigned long max_elapsed_dispatch; + +/* + * tunables + */ +static int cfq_quantum = 4; /* max queue in one round of service */ +static int cfq_queued = 8; /* minimum rq allocate limit per-queue*/ +static int cfq_service = HZ; /* period over which service is avg */ +static int cfq_fifo_expire_r = HZ / 2; /* fifo timeout for sync requests */ +static int cfq_fifo_expire_w = 5 * HZ; /* fifo timeout for async requests */ +static int cfq_fifo_rate = HZ / 8; /* fifo expiry rate */ +static int cfq_back_max = 16 * 1024; /* maximum backwards seek, in KiB */ +static int cfq_back_penalty = 2; /* penalty of a backwards seek */ + +/* + * for the hash of cfqq inside the cfqd + */ +#define CFQ_QHASH_SHIFT 6 +#define CFQ_QHASH_ENTRIES (1 << CFQ_QHASH_SHIFT) +#define list_entry_qhash(entry) hlist_entry((entry), struct cfq_queue, cfq_hash) + +/* + * for the hash of crq inside the cfqq + */ +#define CFQ_MHASH_SHIFT 6 +#define CFQ_MHASH_BLOCK(sec) ((sec) >> 3) +#define CFQ_MHASH_ENTRIES (1 << CFQ_MHASH_SHIFT) +#define CFQ_MHASH_FN(sec) hash_long(CFQ_MHASH_BLOCK(sec), CFQ_MHASH_SHIFT) +#define rq_hash_key(rq) ((rq)->sector + (rq)->nr_sectors) +#define list_entry_hash(ptr) hlist_entry((ptr), struct cfq_rq, hash) + +#define list_entry_cfqq(ptr) list_entry((ptr), struct cfq_queue, cfq_list) + +#define RQ_DATA(rq) (rq)->elevator_private + +/* + * rb-tree defines + */ +#define RB_NONE (2) +#define RB_EMPTY(node) ((node)->rb_node == NULL) +#define RB_CLEAR_COLOR(node) (node)->rb_color = RB_NONE +#define RB_CLEAR(node) do { \ + (node)->rb_parent = NULL; \ + RB_CLEAR_COLOR((node)); \ + (node)->rb_right = NULL; \ + (node)->rb_left = NULL; \ +} while (0) +#define RB_CLEAR_ROOT(root) ((root)->rb_node = NULL) +#define ON_RB(node) ((node)->rb_color != RB_NONE) +#define rb_entry_crq(node) rb_entry((node), struct cfq_rq, rb_node) +#define rq_rb_key(rq) (rq)->sector + +/* + * threshold for switching off non-tag accounting + */ +#define CFQ_MAX_TAG (4) + +/* + * sort key types and names + */ +enum { + CFQ_KEY_PGID, + CFQ_KEY_TGID, + CFQ_KEY_UID, + CFQ_KEY_GID, + CFQ_KEY_LAST, +}; + +static char *cfq_key_types[] = { "pgid", "tgid", "uid", "gid", NULL }; + +static kmem_cache_t *crq_pool; +static kmem_cache_t *cfq_pool; +static kmem_cache_t *cfq_ioc_pool; + +struct cfq_data { + struct list_head rr_list; + struct list_head empty_list; + + struct hlist_head *cfq_hash; + struct hlist_head *crq_hash; + + /* queues on rr_list (ie they have pending requests */ + unsigned int busy_queues; + + unsigned int max_queued; + + atomic_t ref; + + int key_type; + + mempool_t *crq_pool; + + request_queue_t *queue; + + sector_t last_sector; + + int rq_in_driver; + + /* + * tunables, see top of file + */ + unsigned int cfq_quantum; + unsigned int cfq_queued; + unsigned int cfq_fifo_expire_r; + unsigned int cfq_fifo_expire_w; + unsigned int cfq_fifo_batch_expire; + unsigned int cfq_back_penalty; + unsigned int cfq_back_max; + unsigned int find_best_crq; + + unsigned int cfq_tagged; +}; + +struct cfq_queue { + /* reference count */ + atomic_t ref; + /* parent cfq_data */ + struct cfq_data *cfqd; + /* hash of mergeable requests */ + struct hlist_node cfq_hash; + /* hash key */ + unsigned long key; + /* whether queue is on rr (or empty) list */ + int on_rr; + /* on either rr or empty list of cfqd */ + struct list_head cfq_list; + /* sorted list of pending requests */ + struct rb_root sort_list; + /* if fifo isn't expired, next request to serve */ + struct cfq_rq *next_crq; + /* requests queued in sort_list */ + int queued[2]; + /* currently allocated requests */ + int allocated[2]; + /* fifo list of requests in sort_list */ + struct list_head fifo[2]; + /* last time fifo expired */ + unsigned long last_fifo_expire; + + int key_type; + + unsigned long service_start; + unsigned long service_used; + + unsigned int max_rate; + + /* number of requests that have been handed to the driver */ + int in_flight; + /* number of currently allocated requests */ + int alloc_limit[2]; +}; + +struct cfq_rq { + struct rb_node rb_node; + sector_t rb_key; + struct request *request; + struct hlist_node hash; + + struct cfq_queue *cfq_queue; + struct cfq_io_context *io_context; + + unsigned long service_start; + unsigned long queue_start; + + unsigned int in_flight : 1; + unsigned int accounted : 1; + unsigned int is_sync : 1; + unsigned int is_write : 1; +}; + +static struct cfq_queue *cfq_find_cfq_hash(struct cfq_data *, unsigned long); +static void cfq_dispatch_sort(request_queue_t *, struct cfq_rq *); +static void cfq_update_next_crq(struct cfq_rq *); +static void cfq_put_cfqd(struct cfq_data *cfqd); + +/* + * what the fairness is based on (ie how processes are grouped and + * differentiated) + */ +static inline unsigned long +cfq_hash_key(struct cfq_data *cfqd, struct task_struct *tsk) +{ + /* + * optimize this so that ->key_type is the offset into the struct + */ + switch (cfqd->key_type) { + case CFQ_KEY_PGID: + return process_group(tsk); + default: + case CFQ_KEY_TGID: + return tsk->tgid; + case CFQ_KEY_UID: + return tsk->uid; + case CFQ_KEY_GID: + return tsk->gid; + } +} + +/* + * lots of deadline iosched dupes, can be abstracted later... + */ +static inline void cfq_del_crq_hash(struct cfq_rq *crq) +{ + hlist_del_init(&crq->hash); +} + +static void cfq_remove_merge_hints(request_queue_t *q, struct cfq_rq *crq) +{ + cfq_del_crq_hash(crq); + + if (q->last_merge == crq->request) + q->last_merge = NULL; + + cfq_update_next_crq(crq); +} + +static inline void cfq_add_crq_hash(struct cfq_data *cfqd, struct cfq_rq *crq) +{ + const int hash_idx = CFQ_MHASH_FN(rq_hash_key(crq->request)); + + BUG_ON(!hlist_unhashed(&crq->hash)); + + hlist_add_head(&crq->hash, &cfqd->crq_hash[hash_idx]); +} + +static struct request *cfq_find_rq_hash(struct cfq_data *cfqd, sector_t offset) +{ + struct hlist_head *hash_list = &cfqd->crq_hash[CFQ_MHASH_FN(offset)]; + struct hlist_node *entry, *next; + + hlist_for_each_safe(entry, next, hash_list) { + struct cfq_rq *crq = list_entry_hash(entry); + struct request *__rq = crq->request; + + BUG_ON(hlist_unhashed(&crq->hash)); + + if (!rq_mergeable(__rq)) { + cfq_del_crq_hash(crq); + continue; + } + + if (rq_hash_key(__rq) == offset) + return __rq; + } + + return NULL; +} + +/* + * Lifted from AS - choose which of crq1 and crq2 that is best served now. + * We choose the request that is closest to the head right now. Distance + * behind the head are penalized and only allowed to a certain extent. + */ +static struct cfq_rq * +cfq_choose_req(struct cfq_data *cfqd, struct cfq_rq *crq1, struct cfq_rq *crq2) +{ + sector_t last, s1, s2, d1 = 0, d2 = 0; + int r1_wrap = 0, r2_wrap = 0; /* requests are behind the disk head */ + unsigned long back_max; + + if (crq1 == NULL || crq1 == crq2) + return crq2; + if (crq2 == NULL) + return crq1; + + s1 = crq1->request->sector; + s2 = crq2->request->sector; + + last = cfqd->last_sector; + +#if 0 + if (!list_empty(&cfqd->queue->queue_head)) { + struct list_head *entry = &cfqd->queue->queue_head; + unsigned long distance = ~0UL; + struct request *rq; + + while ((entry = entry->prev) != &cfqd->queue->queue_head) { + rq = list_entry_rq(entry); + + if (blk_barrier_rq(rq)) + break; + + if (distance < abs(s1 - rq->sector + rq->nr_sectors)) { + distance = abs(s1 - rq->sector +rq->nr_sectors); + last = rq->sector + rq->nr_sectors; + } + if (distance < abs(s2 - rq->sector + rq->nr_sectors)) { + distance = abs(s2 - rq->sector +rq->nr_sectors); + last = rq->sector + rq->nr_sectors; + } + } + } +#endif + + /* + * by definition, 1KiB is 2 sectors + */ + back_max = cfqd->cfq_back_max * 2; + + /* + * Strict one way elevator _except_ in the case where we allow + * short backward seeks which are biased as twice the cost of a + * similar forward seek. + */ + if (s1 >= last) + d1 = s1 - last; + else if (s1 + back_max >= last) + d1 = (last - s1) * cfqd->cfq_back_penalty; + else + r1_wrap = 1; + + if (s2 >= last) + d2 = s2 - last; + else if (s2 + back_max >= last) + d2 = (last - s2) * cfqd->cfq_back_penalty; + else + r2_wrap = 1; + + /* Found required data */ + if (!r1_wrap && r2_wrap) + return crq1; + else if (!r2_wrap && r1_wrap) + return crq2; + else if (r1_wrap && r2_wrap) { + /* both behind the head */ + if (s1 <= s2) + return crq1; + else + return crq2; + } + + /* Both requests in front of the head */ + if (d1 < d2) + return crq1; + else if (d2 < d1) + return crq2; + else { + if (s1 >= s2) + return crq1; + else + return crq2; + } +} + +/* + * would be nice to take fifo expire time into account as well + */ +static struct cfq_rq * +cfq_find_next_crq(struct cfq_data *cfqd, struct cfq_queue *cfqq, + struct cfq_rq *last) +{ + struct cfq_rq *crq_next = NULL, *crq_prev = NULL; + struct rb_node *rbnext, *rbprev; + + if (!ON_RB(&last->rb_node)) + return NULL; + + if ((rbnext = rb_next(&last->rb_node)) == NULL) + rbnext = rb_first(&cfqq->sort_list); + + rbprev = rb_prev(&last->rb_node); + + if (rbprev) + crq_prev = rb_entry_crq(rbprev); + if (rbnext) + crq_next = rb_entry_crq(rbnext); + + return cfq_choose_req(cfqd, crq_next, crq_prev); +} + +static void cfq_update_next_crq(struct cfq_rq *crq) +{ + struct cfq_queue *cfqq = crq->cfq_queue; + + if (cfqq->next_crq == crq) + cfqq->next_crq = cfq_find_next_crq(cfqq->cfqd, cfqq, crq); +} + +static int cfq_check_sort_rr_list(struct cfq_queue *cfqq) +{ + struct list_head *head = &cfqq->cfqd->rr_list; + struct list_head *next, *prev; + + /* + * list might still be ordered + */ + next = cfqq->cfq_list.next; + if (next != head) { + struct cfq_queue *cnext = list_entry_cfqq(next); + + if (cfqq->service_used > cnext->service_used) + return 1; + } + + prev = cfqq->cfq_list.prev; + if (prev != head) { + struct cfq_queue *cprev = list_entry_cfqq(prev); + + if (cfqq->service_used < cprev->service_used) + return 1; + } + + return 0; +} + +static void cfq_sort_rr_list(struct cfq_queue *cfqq, int new_queue) +{ + struct list_head *entry = &cfqq->cfqd->rr_list; + + if (!cfqq->on_rr) + return; + if (!new_queue && !cfq_check_sort_rr_list(cfqq)) + return; + + list_del(&cfqq->cfq_list); + + /* + * sort by our mean service_used, sub-sort by in-flight requests + */ + while ((entry = entry->prev) != &cfqq->cfqd->rr_list) { + struct cfq_queue *__cfqq = list_entry_cfqq(entry); + + if (cfqq->service_used > __cfqq->service_used) + break; + else if (cfqq->service_used == __cfqq->service_used) { + struct list_head *prv; + + while ((prv = entry->prev) != &cfqq->cfqd->rr_list) { + __cfqq = list_entry_cfqq(prv); + + WARN_ON(__cfqq->service_used > cfqq->service_used); + if (cfqq->service_used != __cfqq->service_used) + break; + if (cfqq->in_flight > __cfqq->in_flight) + break; + + entry = prv; + } + } + } + + list_add(&cfqq->cfq_list, entry); +} + +/* + * add to busy list of queues for service, trying to be fair in ordering + * the pending list according to requests serviced + */ +static inline void +cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + /* + * it's currently on the empty list + */ + cfqq->on_rr = 1; + cfqd->busy_queues++; + + if (time_after(jiffies, cfqq->service_start + cfq_service)) + cfqq->service_used >>= 3; + + cfq_sort_rr_list(cfqq, 1); +} + +static inline void +cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) +{ + list_move(&cfqq->cfq_list, &cfqd->empty_list); + cfqq->on_rr = 0; + + BUG_ON(!cfqd->busy_queues); + cfqd->busy_queues--; +} + +/* + * rb tree support functions + */ +static inline void cfq_del_crq_rb(struct cfq_rq *crq) +{ + struct cfq_queue *cfqq = crq->cfq_queue; + + if (ON_RB(&crq->rb_node)) { + struct cfq_data *cfqd = cfqq->cfqd; + + BUG_ON(!cfqq->queued[crq->is_sync]); + + cfq_update_next_crq(crq); + + cfqq->queued[crq->is_sync]--; + rb_erase(&crq->rb_node, &cfqq->sort_list); + RB_CLEAR_COLOR(&crq->rb_node); + + if (RB_EMPTY(&cfqq->sort_list) && cfqq->on_rr) + cfq_del_cfqq_rr(cfqd, cfqq); + } +} + +static struct cfq_rq * +__cfq_add_crq_rb(struct cfq_rq *crq) +{ + struct rb_node **p = &crq->cfq_queue->sort_list.rb_node; + struct rb_node *parent = NULL; + struct cfq_rq *__crq; + + while (*p) { + parent = *p; + __crq = rb_entry_crq(parent); + + if (crq->rb_key < __crq->rb_key) + p = &(*p)->rb_left; + else if (crq->rb_key > __crq->rb_key) + p = &(*p)->rb_right; + else + return __crq; + } + + rb_link_node(&crq->rb_node, parent, p); + return NULL; +} + +static void cfq_add_crq_rb(struct cfq_rq *crq) +{ + struct cfq_queue *cfqq = crq->cfq_queue; + struct cfq_data *cfqd = cfqq->cfqd; + struct request *rq = crq->request; + struct cfq_rq *__alias; + + crq->rb_key = rq_rb_key(rq); + cfqq->queued[crq->is_sync]++; + + /* + * looks a little odd, but the first insert might return an alias. + * if that happens, put the alias on the dispatch list + */ + while ((__alias = __cfq_add_crq_rb(crq)) != NULL) + cfq_dispatch_sort(cfqd->queue, __alias); + + rb_insert_color(&crq->rb_node, &cfqq->sort_list); + + if (!cfqq->on_rr) + cfq_add_cfqq_rr(cfqd, cfqq); + + /* + * check if this request is a better next-serve candidate + */ + cfqq->next_crq = cfq_choose_req(cfqd, cfqq->next_crq, crq); +} + +static inline void +cfq_reposition_crq_rb(struct cfq_queue *cfqq, struct cfq_rq *crq) +{ + if (ON_RB(&crq->rb_node)) { + rb_erase(&crq->rb_node, &cfqq->sort_list); + cfqq->queued[crq->is_sync]--; + } + + cfq_add_crq_rb(crq); +} + +static struct request * +cfq_find_rq_rb(struct cfq_data *cfqd, sector_t sector) +{ + const unsigned long key = cfq_hash_key(cfqd, current); + struct cfq_queue *cfqq = cfq_find_cfq_hash(cfqd, key); + struct rb_node *n; + + if (!cfqq) + goto out; + + n = cfqq->sort_list.rb_node; + while (n) { + struct cfq_rq *crq = rb_entry_crq(n); + + if (sector < crq->rb_key) + n = n->rb_left; + else if (sector > crq->rb_key) + n = n->rb_right; + else + return crq->request; + } + +out: + return NULL; +} + +static void cfq_deactivate_request(request_queue_t *q, struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + + if (crq) { + struct cfq_queue *cfqq = crq->cfq_queue; + + if (cfqq->cfqd->cfq_tagged) { + cfqq->service_used--; + cfq_sort_rr_list(cfqq, 0); + } + + if (crq->accounted) { + crq->accounted = 0; + cfqq->cfqd->rq_in_driver--; + } + } +} + +/* + * make sure the service time gets corrected on reissue of this request + */ +static void cfq_requeue_request(request_queue_t *q, struct request *rq) +{ + cfq_deactivate_request(q, rq); + list_add(&rq->queuelist, &q->queue_head); +} + +static void cfq_remove_request(request_queue_t *q, struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + + if (crq) { + cfq_remove_merge_hints(q, crq); + list_del_init(&rq->queuelist); + + if (crq->cfq_queue) + cfq_del_crq_rb(crq); + } +} + +static int +cfq_merge(request_queue_t *q, struct request **req, struct bio *bio) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct request *__rq; + int ret; + + ret = elv_try_last_merge(q, bio); + if (ret != ELEVATOR_NO_MERGE) { + __rq = q->last_merge; + goto out_insert; + } + + __rq = cfq_find_rq_hash(cfqd, bio->bi_sector); + if (__rq) { + BUG_ON(__rq->sector + __rq->nr_sectors != bio->bi_sector); + + if (elv_rq_merge_ok(__rq, bio)) { + ret = ELEVATOR_BACK_MERGE; + goto out; + } + } + + __rq = cfq_find_rq_rb(cfqd, bio->bi_sector + bio_sectors(bio)); + if (__rq) { + if (elv_rq_merge_ok(__rq, bio)) { + ret = ELEVATOR_FRONT_MERGE; + goto out; + } + } + + return ELEVATOR_NO_MERGE; +out: + q->last_merge = __rq; +out_insert: + *req = __rq; + return ret; +} + +static void cfq_merged_request(request_queue_t *q, struct request *req) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_rq *crq = RQ_DATA(req); + + cfq_del_crq_hash(crq); + cfq_add_crq_hash(cfqd, crq); + + if (ON_RB(&crq->rb_node) && (rq_rb_key(req) != crq->rb_key)) { + struct cfq_queue *cfqq = crq->cfq_queue; + + cfq_update_next_crq(crq); + cfq_reposition_crq_rb(cfqq, crq); + } + + q->last_merge = req; +} + +static void +cfq_merged_requests(request_queue_t *q, struct request *rq, + struct request *next) +{ + struct cfq_rq *crq = RQ_DATA(rq); + struct cfq_rq *cnext = RQ_DATA(next); + + cfq_merged_request(q, rq); + + if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist)) { + if (time_before(cnext->queue_start, crq->queue_start)) { + list_move(&rq->queuelist, &next->queuelist); + crq->queue_start = cnext->queue_start; + } + } + + cfq_update_next_crq(cnext); + cfq_remove_request(q, next); +} + +/* + * we dispatch cfqd->cfq_quantum requests in total from the rr_list queues, + * this function sector sorts the selected request to minimize seeks. we start + * at cfqd->last_sector, not 0. + */ +static void cfq_dispatch_sort(request_queue_t *q, struct cfq_rq *crq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_queue *cfqq = crq->cfq_queue; + struct list_head *head = &q->queue_head, *entry = head; + struct request *__rq; + sector_t last; + + cfq_del_crq_rb(crq); + cfq_remove_merge_hints(q, crq); + list_del(&crq->request->queuelist); + + last = cfqd->last_sector; + while ((entry = entry->prev) != head) { + __rq = list_entry_rq(entry); + + if (blk_barrier_rq(crq->request)) + break; + if (!blk_fs_request(crq->request)) + break; + + if (crq->request->sector > __rq->sector) + break; + if (__rq->sector > last && crq->request->sector < last) { + last = crq->request->sector; + break; + } + } + + cfqd->last_sector = last; + crq->in_flight = 1; + cfqq->in_flight++; + list_add(&crq->request->queuelist, entry); +} + +/* + * return expired entry, or NULL to just start from scratch in rbtree + */ +static inline struct cfq_rq *cfq_check_fifo(struct cfq_queue *cfqq) +{ + struct cfq_data *cfqd = cfqq->cfqd; + const int reads = !list_empty(&cfqq->fifo[0]); + const int writes = !list_empty(&cfqq->fifo[1]); + unsigned long now = jiffies; + struct cfq_rq *crq; + + if (time_before(now, cfqq->last_fifo_expire + cfqd->cfq_fifo_batch_expire)) + return NULL; + + crq = RQ_DATA(list_entry(cfqq->fifo[0].next, struct request, queuelist)); + if (reads && time_after(now, crq->queue_start + cfqd->cfq_fifo_expire_r)) { + cfqq->last_fifo_expire = now; + return crq; + } + + crq = RQ_DATA(list_entry(cfqq->fifo[1].next, struct request, queuelist)); + if (writes && time_after(now, crq->queue_start + cfqd->cfq_fifo_expire_w)) { + cfqq->last_fifo_expire = now; + return crq; + } + + return NULL; +} + +/* + * dispatch a single request from given queue + */ +static inline void +cfq_dispatch_request(request_queue_t *q, struct cfq_data *cfqd, + struct cfq_queue *cfqq) +{ + struct cfq_rq *crq; + + /* + * follow expired path, else get first next available + */ + if ((crq = cfq_check_fifo(cfqq)) == NULL) { + if (cfqd->find_best_crq) + crq = cfqq->next_crq; + else + crq = rb_entry_crq(rb_first(&cfqq->sort_list)); + } + + cfqd->last_sector = crq->request->sector + crq->request->nr_sectors; + + /* + * finally, insert request into driver list + */ + cfq_dispatch_sort(q, crq); +} + +static int cfq_dispatch_requests(request_queue_t *q, int max_dispatch) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_queue *cfqq; + struct list_head *entry, *tmp; + int queued, busy_queues, first_round; + + if (list_empty(&cfqd->rr_list)) + return 0; + + queued = 0; + first_round = 1; +restart: + busy_queues = 0; + list_for_each_safe(entry, tmp, &cfqd->rr_list) { + cfqq = list_entry_cfqq(entry); + + BUG_ON(RB_EMPTY(&cfqq->sort_list)); + + /* + * first round of queueing, only select from queues that + * don't already have io in-flight + */ + if (first_round && cfqq->in_flight) + continue; + + cfq_dispatch_request(q, cfqd, cfqq); + + if (!RB_EMPTY(&cfqq->sort_list)) + busy_queues++; + + queued++; + } + + if ((queued < max_dispatch) && (busy_queues || first_round)) { + first_round = 0; + goto restart; + } + + return queued; +} + +static inline void cfq_account_dispatch(struct cfq_rq *crq) +{ + struct cfq_queue *cfqq = crq->cfq_queue; + struct cfq_data *cfqd = cfqq->cfqd; + unsigned long now, elapsed; + + if (!blk_fs_request(crq->request)) + return; + + /* + * accounted bit is necessary since some drivers will call + * elv_next_request() many times for the same request (eg ide) + */ + if (crq->accounted) + return; + + now = jiffies; + if (cfqq->service_start == ~0UL) + cfqq->service_start = now; + + /* + * on drives with tagged command queueing, command turn-around time + * doesn't necessarily reflect the time spent processing this very + * command inside the drive. so do the accounting differently there, + * by just sorting on the number of requests + */ + if (cfqd->cfq_tagged) { + if (time_after(now, cfqq->service_start + cfq_service)) { + cfqq->service_start = now; + cfqq->service_used /= 10; + } + + cfqq->service_used++; + cfq_sort_rr_list(cfqq, 0); + } + + elapsed = now - crq->queue_start; + if (elapsed > max_elapsed_dispatch) + max_elapsed_dispatch = elapsed; + + crq->accounted = 1; + crq->service_start = now; + + if (++cfqd->rq_in_driver >= CFQ_MAX_TAG && !cfqd->cfq_tagged) { + cfqq->cfqd->cfq_tagged = 1; + printk("cfq: depth %d reached, tagging now on\n", CFQ_MAX_TAG); + } +} + +static inline void +cfq_account_completion(struct cfq_queue *cfqq, struct cfq_rq *crq) +{ + struct cfq_data *cfqd = cfqq->cfqd; + + if (!crq->accounted) + return; + + WARN_ON(!cfqd->rq_in_driver); + cfqd->rq_in_driver--; + + if (!cfqd->cfq_tagged) { + unsigned long now = jiffies; + unsigned long duration = now - crq->service_start; + + if (time_after(now, cfqq->service_start + cfq_service)) { + cfqq->service_start = now; + cfqq->service_used >>= 3; + } + + cfqq->service_used += duration; + cfq_sort_rr_list(cfqq, 0); + + if (duration > max_elapsed_crq) + max_elapsed_crq = duration; + } +} + +static struct request *cfq_next_request(request_queue_t *q) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct request *rq; + + if (!list_empty(&q->queue_head)) { + struct cfq_rq *crq; +dispatch: + rq = list_entry_rq(q->queue_head.next); + + if ((crq = RQ_DATA(rq)) != NULL) { + cfq_remove_merge_hints(q, crq); + cfq_account_dispatch(crq); + } + + return rq; + } + + if (cfq_dispatch_requests(q, cfqd->cfq_quantum)) + goto dispatch; + + return NULL; +} + +/* + * task holds one reference to the queue, dropped when task exits. each crq + * in-flight on this queue also holds a reference, dropped when crq is freed. + * + * queue lock must be held here. + */ +static void cfq_put_queue(struct cfq_queue *cfqq) +{ + BUG_ON(!atomic_read(&cfqq->ref)); + + if (!atomic_dec_and_test(&cfqq->ref)) + return; + + BUG_ON(rb_first(&cfqq->sort_list)); + BUG_ON(cfqq->on_rr); + + cfq_put_cfqd(cfqq->cfqd); + + /* + * it's on the empty list and still hashed + */ + list_del(&cfqq->cfq_list); + hlist_del(&cfqq->cfq_hash); + kmem_cache_free(cfq_pool, cfqq); +} + +static inline struct cfq_queue * +__cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned long key, const int hashval) +{ + struct hlist_head *hash_list = &cfqd->cfq_hash[hashval]; + struct hlist_node *entry, *next; + + hlist_for_each_safe(entry, next, hash_list) { + struct cfq_queue *__cfqq = list_entry_qhash(entry); + + if (__cfqq->key == key) + return __cfqq; + } + + return NULL; +} + +static struct cfq_queue * +cfq_find_cfq_hash(struct cfq_data *cfqd, unsigned long key) +{ + return __cfq_find_cfq_hash(cfqd, key, hash_long(key, CFQ_QHASH_SHIFT)); +} + +static inline void +cfq_rehash_cfqq(struct cfq_data *cfqd, struct cfq_queue **cfqq, + struct cfq_io_context *cic) +{ + unsigned long hashkey = cfq_hash_key(cfqd, current); + unsigned long hashval = hash_long(hashkey, CFQ_QHASH_SHIFT); + struct cfq_queue *__cfqq; + unsigned long flags; + + spin_lock_irqsave(cfqd->queue->queue_lock, flags); + + hlist_del(&(*cfqq)->cfq_hash); + + __cfqq = __cfq_find_cfq_hash(cfqd, hashkey, hashval); + if (!__cfqq || __cfqq == *cfqq) { + __cfqq = *cfqq; + hlist_add_head(&__cfqq->cfq_hash, &cfqd->cfq_hash[hashval]); + __cfqq->key_type = cfqd->key_type; + } else { + atomic_inc(&__cfqq->ref); + cic->cfqq = __cfqq; + cfq_put_queue(*cfqq); + *cfqq = __cfqq; + } + + cic->cfqq = __cfqq; + spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); +} + +static void cfq_free_io_context(struct cfq_io_context *cic) +{ + kmem_cache_free(cfq_ioc_pool, cic); +} + +/* + * locking hierarchy is: io_context lock -> queue locks + */ +static void cfq_exit_io_context(struct cfq_io_context *cic) +{ + struct cfq_queue *cfqq = cic->cfqq; + struct list_head *entry = &cic->list; + request_queue_t *q; + unsigned long flags; + + /* + * put the reference this task is holding to the various queues + */ + spin_lock_irqsave(&cic->ioc->lock, flags); + while ((entry = cic->list.next) != &cic->list) { + struct cfq_io_context *__cic; + + __cic = list_entry(entry, struct cfq_io_context, list); + list_del(entry); + + q = __cic->cfqq->cfqd->queue; + spin_lock(q->queue_lock); + cfq_put_queue(__cic->cfqq); + spin_unlock(q->queue_lock); + } + + q = cfqq->cfqd->queue; + spin_lock(q->queue_lock); + cfq_put_queue(cfqq); + spin_unlock(q->queue_lock); + + cic->cfqq = NULL; + spin_unlock_irqrestore(&cic->ioc->lock, flags); +} + +static struct cfq_io_context *cfq_alloc_io_context(int gfp_flags) +{ + struct cfq_io_context *cic = kmem_cache_alloc(cfq_ioc_pool, gfp_flags); + + if (cic) { + cic->dtor = cfq_free_io_context; + cic->exit = cfq_exit_io_context; + INIT_LIST_HEAD(&cic->list); + cic->cfqq = NULL; + } + + return cic; +} + +/* + * Setup general io context and cfq io context. There can be several cfq + * io contexts per general io context, if this process is doing io to more + * than one device managed by cfq. Note that caller is holding a reference to + * cfqq, so we don't need to worry about it disappearing + */ +static struct cfq_io_context * +cfq_get_io_context(struct cfq_queue **cfqq, int gfp_flags) +{ + struct cfq_data *cfqd = (*cfqq)->cfqd; + struct cfq_queue *__cfqq = *cfqq; + struct cfq_io_context *cic; + struct io_context *ioc; + + might_sleep_if(gfp_flags & __GFP_WAIT); + + ioc = get_io_context(gfp_flags); + if (!ioc) + return NULL; + + if ((cic = ioc->cic) == NULL) { + cic = cfq_alloc_io_context(gfp_flags); + + if (cic == NULL) + goto err; + + ioc->cic = cic; + cic->ioc = ioc; + cic->cfqq = __cfqq; + atomic_inc(&__cfqq->ref); + } else { + struct cfq_io_context *__cic; + unsigned long flags; + + /* + * since the first cic on the list is actually the head + * itself, need to check this here or we'll duplicate an + * cic per ioc for no reason + */ + if (cic->cfqq == __cfqq) + goto out; + + /* + * cic exists, check if we already are there. linear search + * should be ok here, the list will usually not be more than + * 1 or a few entries long + */ + spin_lock_irqsave(&ioc->lock, flags); + list_for_each_entry(__cic, &cic->list, list) { + /* + * this process is already holding a reference to + * this queue, so no need to get one more + */ + if (__cic->cfqq == __cfqq) { + cic = __cic; + spin_unlock_irqrestore(&ioc->lock, flags); + goto out; + } + } + spin_unlock_irqrestore(&ioc->lock, flags); + + /* + * nope, process doesn't have a cic assoicated with this + * cfqq yet. get a new one and add to list + */ + __cic = cfq_alloc_io_context(gfp_flags); + if (__cic == NULL) + goto err; + + __cic->ioc = ioc; + __cic->cfqq = __cfqq; + atomic_inc(&__cfqq->ref); + spin_lock_irqsave(&ioc->lock, flags); + list_add(&__cic->list, &cic->list); + spin_unlock_irqrestore(&ioc->lock, flags); + + cic = __cic; + *cfqq = __cfqq; + } + +out: + /* + * if key_type has been changed on the fly, we lazily rehash + * each queue at lookup time + */ + if ((*cfqq)->key_type != cfqd->key_type) + cfq_rehash_cfqq(cfqd, cfqq, cic); + + return cic; +err: + put_io_context(ioc); + return NULL; +} + +static struct cfq_queue * +__cfq_get_queue(struct cfq_data *cfqd, unsigned long key, int gfp_mask) +{ + const int hashval = hash_long(key, CFQ_QHASH_SHIFT); + struct cfq_queue *cfqq, *new_cfqq = NULL; + +retry: + cfqq = __cfq_find_cfq_hash(cfqd, key, hashval); + + if (!cfqq) { + if (new_cfqq) { + cfqq = new_cfqq; + new_cfqq = NULL; + } else if (gfp_mask & __GFP_WAIT) { + spin_unlock_irq(cfqd->queue->queue_lock); + new_cfqq = kmem_cache_alloc(cfq_pool, gfp_mask); + spin_lock_irq(cfqd->queue->queue_lock); + goto retry; + } else + goto out; + + memset(cfqq, 0, sizeof(*cfqq)); + + INIT_HLIST_NODE(&cfqq->cfq_hash); + INIT_LIST_HEAD(&cfqq->cfq_list); + RB_CLEAR_ROOT(&cfqq->sort_list); + INIT_LIST_HEAD(&cfqq->fifo[0]); + INIT_LIST_HEAD(&cfqq->fifo[1]); + + cfqq->key = key; + hlist_add_head(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]); + atomic_set(&cfqq->ref, 0); + cfqq->cfqd = cfqd; + atomic_inc(&cfqd->ref); + cfqq->key_type = cfqd->key_type; + cfqq->service_start = ~0UL; + } + + if (new_cfqq) + kmem_cache_free(cfq_pool, new_cfqq); + + atomic_inc(&cfqq->ref); +out: + WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq); + return cfqq; +} + +static void cfq_enqueue(struct cfq_data *cfqd, struct cfq_rq *crq) +{ + crq->is_sync = 0; + if (rq_data_dir(crq->request) == READ || current->flags & PF_SYNCWRITE) + crq->is_sync = 1; + + cfq_add_crq_rb(crq); + crq->queue_start = jiffies; + + list_add_tail(&crq->request->queuelist, &crq->cfq_queue->fifo[crq->is_sync]); +} + +static void +cfq_insert_request(request_queue_t *q, struct request *rq, int where) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_rq *crq = RQ_DATA(rq); + + switch (where) { + case ELEVATOR_INSERT_BACK: + while (cfq_dispatch_requests(q, cfqd->cfq_quantum)) + ; + list_add_tail(&rq->queuelist, &q->queue_head); + break; + case ELEVATOR_INSERT_FRONT: + list_add(&rq->queuelist, &q->queue_head); + break; + case ELEVATOR_INSERT_SORT: + BUG_ON(!blk_fs_request(rq)); + cfq_enqueue(cfqd, crq); + break; + default: + printk("%s: bad insert point %d\n", __FUNCTION__,where); + return; + } + + if (rq_mergeable(rq)) { + cfq_add_crq_hash(cfqd, crq); + + if (!q->last_merge) + q->last_merge = rq; + } +} + +static int cfq_queue_empty(request_queue_t *q) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + + return list_empty(&q->queue_head) && list_empty(&cfqd->rr_list); +} + +static void cfq_completed_request(request_queue_t *q, struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + struct cfq_queue *cfqq; + + if (unlikely(!blk_fs_request(rq))) + return; + + cfqq = crq->cfq_queue; + + if (crq->in_flight) { + WARN_ON(!cfqq->in_flight); + cfqq->in_flight--; + } + + cfq_account_completion(cfqq, crq); +} + +static struct request * +cfq_former_request(request_queue_t *q, struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + struct rb_node *rbprev = rb_prev(&crq->rb_node); + + if (rbprev) + return rb_entry_crq(rbprev)->request; + + return NULL; +} + +static struct request * +cfq_latter_request(request_queue_t *q, struct request *rq) +{ + struct cfq_rq *crq = RQ_DATA(rq); + struct rb_node *rbnext = rb_next(&crq->rb_node); + + if (rbnext) + return rb_entry_crq(rbnext)->request; + + return NULL; +} + +static int cfq_may_queue(request_queue_t *q, int rw) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_queue *cfqq; + int ret = ELV_MQUEUE_MAY; + + if (current->flags & PF_MEMALLOC) + return ELV_MQUEUE_MAY; + + cfqq = cfq_find_cfq_hash(cfqd, cfq_hash_key(cfqd, current)); + if (cfqq) { + int limit = cfqd->max_queued; + + if (cfqq->allocated[rw] < cfqd->cfq_queued) + return ELV_MQUEUE_MUST; + + if (cfqd->busy_queues) + limit = q->nr_requests / cfqd->busy_queues; + + if (limit < cfqd->cfq_queued) + limit = cfqd->cfq_queued; + else if (limit > cfqd->max_queued) + limit = cfqd->max_queued; + + if (cfqq->allocated[rw] >= limit) { + if (limit > cfqq->alloc_limit[rw]) + cfqq->alloc_limit[rw] = limit; + + ret = ELV_MQUEUE_NO; + } + } + + return ret; +} + +static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq) +{ + struct request_list *rl = &q->rq; + const int write = waitqueue_active(&rl->wait[WRITE]); + const int read = waitqueue_active(&rl->wait[READ]); + + if (read && cfqq->allocated[READ] < cfqq->alloc_limit[READ]) + wake_up(&rl->wait[READ]); + if (write && cfqq->allocated[WRITE] < cfqq->alloc_limit[WRITE]) + wake_up(&rl->wait[WRITE]); +} + +/* + * queue lock held here + */ +static void cfq_put_request(request_queue_t *q, struct request *rq) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_rq *crq = RQ_DATA(rq); + + if (crq) { + struct cfq_queue *cfqq = crq->cfq_queue; + + BUG_ON(q->last_merge == rq); + BUG_ON(!hlist_unhashed(&crq->hash)); + + if (crq->io_context) + put_io_context(crq->io_context->ioc); + + BUG_ON(!cfqq->allocated[crq->is_write]); + cfqq->allocated[crq->is_write]--; + + mempool_free(crq, cfqd->crq_pool); + rq->elevator_private = NULL; + + smp_mb(); + cfq_check_waiters(q, cfqq); + cfq_put_queue(cfqq); + } +} + +/* + * Allocate cfq data structures associated with this request. A queue and + */ +static int cfq_set_request(request_queue_t *q, struct request *rq, int gfp_mask) +{ + struct cfq_data *cfqd = q->elevator->elevator_data; + struct cfq_io_context *cic; + const int rw = rq_data_dir(rq); + struct cfq_queue *cfqq, *saved_cfqq; + struct cfq_rq *crq; + unsigned long flags; + + might_sleep_if(gfp_mask & __GFP_WAIT); + + spin_lock_irqsave(q->queue_lock, flags); + + cfqq = __cfq_get_queue(cfqd, cfq_hash_key(cfqd, current), gfp_mask); + if (!cfqq) + goto out_lock; + +repeat: + if (cfqq->allocated[rw] >= cfqd->max_queued) + goto out_lock; + + cfqq->allocated[rw]++; + spin_unlock_irqrestore(q->queue_lock, flags); + + /* + * if hashing type has changed, the cfq_queue might change here. + */ + saved_cfqq = cfqq; + cic = cfq_get_io_context(&cfqq, gfp_mask); + if (!cic) + goto err; + + /* + * repeat allocation checks on queue change + */ + if (unlikely(saved_cfqq != cfqq)) { + spin_lock_irqsave(q->queue_lock, flags); + saved_cfqq->allocated[rw]--; + goto repeat; + } + + crq = mempool_alloc(cfqd->crq_pool, gfp_mask); + if (crq) { + RB_CLEAR(&crq->rb_node); + crq->rb_key = 0; + crq->request = rq; + INIT_HLIST_NODE(&crq->hash); + crq->cfq_queue = cfqq; + crq->io_context = cic; + crq->service_start = crq->queue_start = 0; + crq->in_flight = crq->accounted = crq->is_sync = 0; + crq->is_write = rw; + rq->elevator_private = crq; + cfqq->alloc_limit[rw] = 0; + return 0; + } + + put_io_context(cic->ioc); +err: + spin_lock_irqsave(q->queue_lock, flags); + cfqq->allocated[rw]--; + cfq_put_queue(cfqq); +out_lock: + spin_unlock_irqrestore(q->queue_lock, flags); + return 1; +} + +static void cfq_put_cfqd(struct cfq_data *cfqd) +{ + request_queue_t *q = cfqd->queue; + + if (!atomic_dec_and_test(&cfqd->ref)) + return; + + blk_put_queue(q); + + mempool_destroy(cfqd->crq_pool); + kfree(cfqd->crq_hash); + kfree(cfqd->cfq_hash); + kfree(cfqd); +} + +static void cfq_exit_queue(elevator_t *e) +{ + cfq_put_cfqd(e->elevator_data); +} + +static int cfq_init_queue(request_queue_t *q, elevator_t *e) +{ + struct cfq_data *cfqd; + int i; + + cfqd = kmalloc(sizeof(*cfqd), GFP_KERNEL); + if (!cfqd) + return -ENOMEM; + + memset(cfqd, 0, sizeof(*cfqd)); + INIT_LIST_HEAD(&cfqd->rr_list); + INIT_LIST_HEAD(&cfqd->empty_list); + + cfqd->crq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_MHASH_ENTRIES, GFP_KERNEL); + if (!cfqd->crq_hash) + goto out_crqhash; + + cfqd->cfq_hash = kmalloc(sizeof(struct hlist_head) * CFQ_QHASH_ENTRIES, GFP_KERNEL); + if (!cfqd->cfq_hash) + goto out_cfqhash; + + cfqd->crq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, crq_pool); + if (!cfqd->crq_pool) + goto out_crqpool; + + for (i = 0; i < CFQ_MHASH_ENTRIES; i++) + INIT_HLIST_HEAD(&cfqd->crq_hash[i]); + for (i = 0; i < CFQ_QHASH_ENTRIES; i++) + INIT_HLIST_HEAD(&cfqd->cfq_hash[i]); + + e->elevator_data = cfqd; + + cfqd->queue = q; + atomic_inc(&q->refcnt); + + /* + * just set it to some high value, we want anyone to be able to queue + * some requests. fairness is handled differently + */ + q->nr_requests = 1024; + cfqd->max_queued = q->nr_requests / 16; + q->nr_batching = cfq_queued; + cfqd->key_type = CFQ_KEY_TGID; + cfqd->find_best_crq = 1; + atomic_set(&cfqd->ref, 1); + + cfqd->cfq_queued = cfq_queued; + cfqd->cfq_quantum = cfq_quantum; + cfqd->cfq_fifo_expire_r = cfq_fifo_expire_r; + cfqd->cfq_fifo_expire_w = cfq_fifo_expire_w; + cfqd->cfq_fifo_batch_expire = cfq_fifo_rate; + cfqd->cfq_back_max = cfq_back_max; + cfqd->cfq_back_penalty = cfq_back_penalty; + + return 0; +out_crqpool: + kfree(cfqd->cfq_hash); +out_cfqhash: + kfree(cfqd->crq_hash); +out_crqhash: + kfree(cfqd); + return -ENOMEM; +} + +static void cfq_slab_kill(void) +{ + if (crq_pool) + kmem_cache_destroy(crq_pool); + if (cfq_pool) + kmem_cache_destroy(cfq_pool); + if (cfq_ioc_pool) + kmem_cache_destroy(cfq_ioc_pool); +} + +static int __init cfq_slab_setup(void) +{ + crq_pool = kmem_cache_create("crq_pool", sizeof(struct cfq_rq), 0, 0, + NULL, NULL); + if (!crq_pool) + goto fail; + + cfq_pool = kmem_cache_create("cfq_pool", sizeof(struct cfq_queue), 0, 0, + NULL, NULL); + if (!cfq_pool) + goto fail; + + cfq_ioc_pool = kmem_cache_create("cfq_ioc_pool", + sizeof(struct cfq_io_context), 0, 0, NULL, NULL); + if (!cfq_ioc_pool) + goto fail; + + return 0; +fail: + cfq_slab_kill(); + return -ENOMEM; +} + + +/* + * sysfs parts below --> + */ +struct cfq_fs_entry { + struct attribute attr; + ssize_t (*show)(struct cfq_data *, char *); + ssize_t (*store)(struct cfq_data *, const char *, size_t); +}; + +static ssize_t +cfq_var_show(unsigned int var, char *page) +{ + return sprintf(page, "%d\n", var); +} + +static ssize_t +cfq_var_store(unsigned int *var, const char *page, size_t count) +{ + char *p = (char *) page; + + *var = simple_strtoul(p, &p, 10); + return count; +} + +static ssize_t +cfq_clear_elapsed(struct cfq_data *cfqd, const char *page, size_t count) +{ + max_elapsed_dispatch = max_elapsed_crq = 0; + return count; +} + +static ssize_t +cfq_set_key_type(struct cfq_data *cfqd, const char *page, size_t count) +{ + spin_lock_irq(cfqd->queue->queue_lock); + if (!strncmp(page, "pgid", 4)) + cfqd->key_type = CFQ_KEY_PGID; + else if (!strncmp(page, "tgid", 4)) + cfqd->key_type = CFQ_KEY_TGID; + else if (!strncmp(page, "uid", 3)) + cfqd->key_type = CFQ_KEY_UID; + else if (!strncmp(page, "gid", 3)) + cfqd->key_type = CFQ_KEY_GID; + spin_unlock_irq(cfqd->queue->queue_lock); + return count; +} + +static ssize_t +cfq_read_key_type(struct cfq_data *cfqd, char *page) +{ + ssize_t len = 0; + int i; + + for (i = CFQ_KEY_PGID; i < CFQ_KEY_LAST; i++) { + if (cfqd->key_type == i) + len += sprintf(page+len, "[%s] ", cfq_key_types[i]); + else + len += sprintf(page+len, "%s ", cfq_key_types[i]); + } + len += sprintf(page+len, "\n"); + return len; +} + +#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ +static ssize_t __FUNC(struct cfq_data *cfqd, char *page) \ +{ \ + unsigned int __data = __VAR; \ + if (__CONV) \ + __data = jiffies_to_msecs(__data); \ + return cfq_var_show(__data, (page)); \ +} +SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0); +SHOW_FUNCTION(cfq_queued_show, cfqd->cfq_queued, 0); +SHOW_FUNCTION(cfq_fifo_expire_r_show, cfqd->cfq_fifo_expire_r, 1); +SHOW_FUNCTION(cfq_fifo_expire_w_show, cfqd->cfq_fifo_expire_w, 1); +SHOW_FUNCTION(cfq_fifo_batch_expire_show, cfqd->cfq_fifo_batch_expire, 1); +SHOW_FUNCTION(cfq_find_best_show, cfqd->find_best_crq, 0); +SHOW_FUNCTION(cfq_back_max_show, cfqd->cfq_back_max, 0); +SHOW_FUNCTION(cfq_back_penalty_show, cfqd->cfq_back_penalty, 0); +#undef SHOW_FUNCTION + +#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ +static ssize_t __FUNC(struct cfq_data *cfqd, const char *page, size_t count) \ +{ \ + unsigned int __data; \ + int ret = cfq_var_store(&__data, (page), count); \ + if (__data < (MIN)) \ + __data = (MIN); \ + else if (__data > (MAX)) \ + __data = (MAX); \ + if (__CONV) \ + *(__PTR) = msecs_to_jiffies(__data); \ + else \ + *(__PTR) = __data; \ + return ret; \ +} +STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0); +STORE_FUNCTION(cfq_queued_store, &cfqd->cfq_queued, 1, UINT_MAX, 0); +STORE_FUNCTION(cfq_fifo_expire_r_store, &cfqd->cfq_fifo_expire_r, 1, UINT_MAX, 1); +STORE_FUNCTION(cfq_fifo_expire_w_store, &cfqd->cfq_fifo_expire_w, 1, UINT_MAX, 1); +STORE_FUNCTION(cfq_fifo_batch_expire_store, &cfqd->cfq_fifo_batch_expire, 0, UINT_MAX, 1); +STORE_FUNCTION(cfq_find_best_store, &cfqd->find_best_crq, 0, 1, 0); +STORE_FUNCTION(cfq_back_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0); +STORE_FUNCTION(cfq_back_penalty_store, &cfqd->cfq_back_penalty, 1, UINT_MAX, 0); +#undef STORE_FUNCTION + +static struct cfq_fs_entry cfq_quantum_entry = { + .attr = {.name = "quantum", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_quantum_show, + .store = cfq_quantum_store, +}; +static struct cfq_fs_entry cfq_queued_entry = { + .attr = {.name = "queued", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_queued_show, + .store = cfq_queued_store, +}; +static struct cfq_fs_entry cfq_fifo_expire_r_entry = { + .attr = {.name = "fifo_expire_sync", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_fifo_expire_r_show, + .store = cfq_fifo_expire_r_store, +}; +static struct cfq_fs_entry cfq_fifo_expire_w_entry = { + .attr = {.name = "fifo_expire_async", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_fifo_expire_w_show, + .store = cfq_fifo_expire_w_store, +}; +static struct cfq_fs_entry cfq_fifo_batch_expire_entry = { + .attr = {.name = "fifo_batch_expire", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_fifo_batch_expire_show, + .store = cfq_fifo_batch_expire_store, +}; +static struct cfq_fs_entry cfq_find_best_entry = { + .attr = {.name = "find_best_crq", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_find_best_show, + .store = cfq_find_best_store, +}; +static struct cfq_fs_entry cfq_back_max_entry = { + .attr = {.name = "back_seek_max", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_back_max_show, + .store = cfq_back_max_store, +}; +static struct cfq_fs_entry cfq_back_penalty_entry = { + .attr = {.name = "back_seek_penalty", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_back_penalty_show, + .store = cfq_back_penalty_store, +}; +static struct cfq_fs_entry cfq_clear_elapsed_entry = { + .attr = {.name = "clear_elapsed", .mode = S_IWUSR }, + .store = cfq_clear_elapsed, +}; +static struct cfq_fs_entry cfq_key_type_entry = { + .attr = {.name = "key_type", .mode = S_IRUGO | S_IWUSR }, + .show = cfq_read_key_type, + .store = cfq_set_key_type, +}; + +static struct attribute *default_attrs[] = { + &cfq_quantum_entry.attr, + &cfq_queued_entry.attr, + &cfq_fifo_expire_r_entry.attr, + &cfq_fifo_expire_w_entry.attr, + &cfq_fifo_batch_expire_entry.attr, + &cfq_key_type_entry.attr, + &cfq_find_best_entry.attr, + &cfq_back_max_entry.attr, + &cfq_back_penalty_entry.attr, + &cfq_clear_elapsed_entry.attr, + NULL, +}; + +#define to_cfq(atr) container_of((atr), struct cfq_fs_entry, attr) + +static ssize_t +cfq_attr_show(struct kobject *kobj, struct attribute *attr, char *page) +{ + elevator_t *e = container_of(kobj, elevator_t, kobj); + struct cfq_fs_entry *entry = to_cfq(attr); + + if (!entry->show) + return 0; + + return entry->show(e->elevator_data, page); +} + +static ssize_t +cfq_attr_store(struct kobject *kobj, struct attribute *attr, + const char *page, size_t length) +{ + elevator_t *e = container_of(kobj, elevator_t, kobj); + struct cfq_fs_entry *entry = to_cfq(attr); + + if (!entry->store) + return -EINVAL; + + return entry->store(e->elevator_data, page, length); +} + +static struct sysfs_ops cfq_sysfs_ops = { + .show = cfq_attr_show, + .store = cfq_attr_store, +}; + +static struct kobj_type cfq_ktype = { + .sysfs_ops = &cfq_sysfs_ops, + .default_attrs = default_attrs, +}; + +static struct elevator_type iosched_cfq = { + .ops = { + .elevator_merge_fn = cfq_merge, + .elevator_merged_fn = cfq_merged_request, + .elevator_merge_req_fn = cfq_merged_requests, + .elevator_next_req_fn = cfq_next_request, + .elevator_add_req_fn = cfq_insert_request, + .elevator_remove_req_fn = cfq_remove_request, + .elevator_requeue_req_fn = cfq_requeue_request, + .elevator_deactivate_req_fn = cfq_deactivate_request, + .elevator_queue_empty_fn = cfq_queue_empty, + .elevator_completed_req_fn = cfq_completed_request, + .elevator_former_req_fn = cfq_former_request, + .elevator_latter_req_fn = cfq_latter_request, + .elevator_set_req_fn = cfq_set_request, + .elevator_put_req_fn = cfq_put_request, + .elevator_may_queue_fn = cfq_may_queue, + .elevator_init_fn = cfq_init_queue, + .elevator_exit_fn = cfq_exit_queue, + }, + .elevator_ktype = &cfq_ktype, + .elevator_name = "cfq", + .elevator_owner = THIS_MODULE, +}; + +static int __init cfq_init(void) +{ + int ret; + + if (cfq_slab_setup()) + return -ENOMEM; + + ret = elv_register(&iosched_cfq); + if (!ret) { + __module_get(THIS_MODULE); + return 0; + } + + cfq_slab_kill(); + return ret; +} + +static void __exit cfq_exit(void) +{ + cfq_slab_kill(); + elv_unregister(&iosched_cfq); +} + +module_init(cfq_init); +module_exit(cfq_exit); + +MODULE_AUTHOR("Jens Axboe"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler"); |